<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>圆角边框</title>
    <style>
        div {
            width: 100px;
            height: 50px;
            background-color: darkseagreen;
            line-height: 50px;
            text-align: center;
            border-radius: 30%;
        }
    </style>
</head>

<body>
    <div>圆角边框</div>
</body>

</html>